(a) Complete the following chemical equations:
(i) ` Cr_(2) O_(7)^(2-) (aq) + H_(2) S(g) + H^(+) (aq) to `
(ii) ` Cu^(2+)(aq) + I^(-) (aq) to `
(b) How would you account for the following :
(i) The oxidising power of oxoanions are in the order `VO_(2)^(+) lt Cr_(2)O_(7)^(2-) lt Mn O_(4)^(-) `
(ii) The third ionization enthalpy of manganess (Z = 25) is exceptionally high.
(iii) `Cr^(2+)` is a stronger reducing agent than `Fe^(2+)`.

Explanation

### Step-by-Step Solution

**(a) Complete the following chemical equations:**

**(i)** The reaction of dichromate ion with hydrogen sulfide in acidic medium:

1. **Identify Reactants and Products**:
- Reactants: \( \text{Cr}_2\text{O}_7^{2-} \) (dichromate ion), \( \text{H}_2\text{S} \) (hydrogen sulfide), \( \text{H}^+ \) (acidic medium).
...